Physicists freeze light, propose optical CPUs

Scientists at Harvard University have discovered how to freeze light, so that it can be used to build an optical computer, theoretically capable of processing information ten times faster than traditional electronics.

The researchers, led by Prof. Lene Hau, has calculated that controlled, coherent processing with light can be performed using ultra-cold atoms known as Bose-Einstein condensates (BECs). Hau outlined her research yesterday at the Physics 2005 conference in Warwick.

Hau has discovered, in her work on slow light, that a BEC can preserve the phase and amplitude of a light pulse. In normal matter, these properties would be smeared out, destroying any information content. If a device can be built that preserves that information, Hau argues, it could be developed into the CPU of an optical computer.

In 2003 Hau's research group slowed light from 186,000 miles per second to around the speed of a bicycle. Later, they froze light altogether, using a cloud of ultra-cold sodium atoms. Dr. Hau argues that frozen light could also have applications for memory storage on optical computers.

As well as frozen light, the group works on other very cold things, including cold atomic beams and superfluidity. ®